Oven cleaner and method of using the same



United States Patent OfiFice 3,335,092 Patented Aug. 8, 1967 3,335,092 OVEN CLEANER AND METHOD OF USING THE SAME Kenneth E. Perry, Wellesley, Mass., assignor to Winfield Brooks Company, Inc., Woburn, Mass., a corporation of Massachusetts No Drawing. Filed Aug. 26, 1965, Ser. No. 482,662 32 Claims. (Cl. 252-158) This application is a continuation-in-part of my application Ser. No. 380,688 filed July 6, 1964, which in turn is a continuation of my application Ser. No. 328,114 filed Dec. 4, 1963, both applications of which are now abandoned.

The present invention relates to an improved cleaning composition for cleaning ovens, grills, griddles, barbeque equipment, pots, pans and other similar surfaces having burnt-on deposits of fat, grease, oil, food, etc., and a method for using the same.

Known commercial oven cleaner compositions contain approximately caustic (sodium hydroxide), which is the maximum amount permitted by government regulation without stringent labelling requirements and which provides the cleaning action. Such compositions are thickened to a thick pasty mass with starch or other thickeners as a base and usually contain a wetting agent. They are applied to the oven cold with a brush using rubber gloves, left on from one to two hours and then cleaned off the cold oven with a cloth or sponge using rubber gloves. If the oven is hot, the material cakes up and is difficult to remove. The manufacturers recommend use on a cold oven.

The disadvantages of these oven cleaner compositions are as follows:

(1) They must be handled with rubber gloves in order to prevent irritation and burning of the skin;

(2) Most of them are thick and hence messy and difficult to apply and to remove and take many hours of hard labor to clean a dirty oven. This is especially disadvantageous and dangerous in view of the highly corrosive and irritating nature of the compositions;

(3) They remove stubborn, badly burnt-on deposits only with great difiiculty.

It is an object of the present invention to provide an improved oven cleaner compositions which is more simple and easy to apply and remove, with which ovens can be cleaned better in only a fraction of the time required with present commercial oven cleaners, and in which the caustic content may be reduced to such a 10W concentration that it is not nearly as corrosive and will not burn the normal skin so that it can be applied and handled without the use of rubber gloves, but which reduced caustic concentration has substantially greater and faster penetrating and cleaning power than known commercial oven cleaners with three times more caustic.

It is a further object to provide an oven cleaner com-' position using a caustic as the principal cleaning ingredient but in which the amount of caustic can be reduced to less than a third of the amount presently required in commercial oven cleaners, while at the same time increasing the cleaning power and rate of cleaning of the reduced amount of caustic over the larger amount in present commercial cleaners, so that better cleaning is achieved in a much faster time.

The corrosiveness and skin burning properties of the composition are reduced to such an extent that it can normally be handled without rubber gloves and accidental contact with clothing, linoleum, furniture, etc. will not be nearly as damaging. Consequently, another object of the invention is to provide an oven cleaner composition which is less corrosive and irritating to the skin and which can be handled without rubber gloves by persons having normal skins to thereby simplify the use thereof.

Another advantage of the oven cleaner composition of the invention is its ability to be applied by spraying and to be stored in conventional, aerosol spray-type cans containing a propellant so that it can simply be sprayed on the oven surfaces in a few moments in the form of a fine, light foam. No obnoxious or dangerous fumes are created during normal application and corrosion problems with respect to storage in cans or other containers are reduced. The foam is neither sticky nor messy and wipes off easily with a damp rag carrying with it the greases and other materials which it has penetrated, softened and removed from the oven surface. The ease with which such foam can be removed is in striking contrast to the difiiculty encountered in wiping off the thick layer of material with the most popular known oven cleaners.

Whereas, it is necessary to leave present commercial oven cleaners on the oven surfaces for at least two hours for adequate penetration and cleaning, better penetration and cleaning is achieved with the oven cleaner of the present invention in a matter of five minutes (only one twenty-fourth the time of the known cleaners), and at the most for stubborn deposits, only twenty minutes (one sixth the time of the known cleaners), after which it can be easily wiped off with no mess.

The present invention is based in one of its aspects on the surprising discovery that a mixture of furfuryl alcohol and tetrahydrofurfuryl alcohol catalyzers and enhances the cleaning action of the sodium hydroxide at elevated temperatures.

The composition of the present invention is applied to surfaces which are at an elevated temperature, e.g. a warm oven, and contains a humectant or water evaporation retardant such as a glycerol or glycol to retard evaporation at the elevated temperature, the present invention being based in another of its aspects on the surprising discovery that the use of such humectant with ovens at an elevated temperature increases substantially the amount and rate of cleaning of the sodium hydroxide and reduces its irritating elfects on the skin with and without the furfuryl alcohol catalysts, and, in still another of its aspects, on the discovery that the application to the oven surfaces at an elevated temperature rather than at room temperature of alkali metal hydroxide in a sufficient amount of water to ionize the hydroxide with or without the furfuryl alcohol catalyst and/ or the humec tant, increases substantially the amount and rate of cleaning without harmful effect.

At the elevated temperature, reaction with the grease and burnt deposits is nearly instantaneous, a most remarkable phenomena. This instantaneous reaction with the grease and deposits on the oven surfaces negates the necessity of thickeners to prevent excessive run-off of the cleaning composition as in many of the most popular commercial oven cleaners.

Accordingly, the method of the present invention in volves broadly spraying on the oven. while it is hot a composition containing as an' essential ingredient an alkali metal hydroxide in Water, leaving such composition on the hot oven for an interval of time and removing the composition from the oven.

The fact that the cleaning composition of the present invention is applied to a hot oven results in convenience to the user in that the oven surfaces can be cleaned without waiting for themto cool. This is especially advantageous for industrial users, whose ovens are beingused constantly and hence are rarely cold. The private housewife can clean deposits created during cooking while she is cleaning her dishes and the oven is still warm. This is particularly advantageous with the popular all-glass front ovens which can become noticeably dirty after even one use.

The composition of the present invention also preferably contains a compatible surfactant to facilitate penetration into the deposits to be removed.

Chem. Co. (surfactant) 1.0 Sulfonate surfactant sold under the trade name Benax 2A1 by Dow Chemical Co 0.1

Propylene glycol 20.0 Furfuryl alcohol 1.4 Tetrahydrofurfuryl alcohol 0.7 Water (including water of NaOH solution) 73.8

1 Exclusive of water in solution.

The caustic was first added to the water with agitation followed by addition of the propylene glycol, surfactants and mixture of furfuryl and tetrahydrofurfuryl alcohols in that order with continued agitation. However, the order and manner of mixing is not important. For example, the alcohols can be added before the glycol.

The composition of the example is a freely flowing liquid. It was packaged in known manner in an aerosol spray-type can with a conventional propellant, e.g. butane. The composition sprayed nicely in the form of a fine foam and was applied as a layer of foam to the inside surfaces of a warm dirty oven, set at 200 F., left on for five minutes and wiped off with a damp rag without gloves. Cleaning was excellent. The foam was applied holding the can nozzle about 8 inches to a foot away from the oven surface with no obnoxious fumes. The same results were achieved by spraying the cleaner of the example on a hot oven with a conventional pressure atomizer.

The propylene glycol can be replaced by any compatible humectant to retard evaporation from contact with the hot oven surface, e.g., any of the glycols, glycerols, etc. Although the use of propylene glycol is highly preferred, the mixture of furfuryl and tetrahydrofurfuryl alcohols catalyzes the cleaning action of the caustic without it. On the other hand, the humectant by virtue of its inherent property of retarding water evaporation, increases the cleaning effect of the sodium hydroxide substantially even without these alcohol catalysts. Also, it inherently reduces the irritating effect of the caustic on the skin with or without these alcohol catalysts.

The amount of humectant may be varied over a Wide range from small amounts, e.g. 1 to 2% by weight, to amounts limited only by the mutual compatibility of the humectant to the rest of the formula.

vThe Benax 2A1 aids in solubilizing the Alipal CO-436 but it can be omitted. Without it, the solution is slightly cloudy due to the limited solubility of the Alipal whereas with it, this cloudiness is removed. However, the cleaning action is just as good with or without it.

Any conventional, non-corrosive, compatible, anionic, cationic or non-ionic surfactant or combinations thereof, which are stable in the cleaning solutions, e.g. sulfate esters, alkyl and aryl sulfonates, amines, quaternary ammonium compounds, sodium N-Coco B-aminopropionate, sodium N-alkyl carboxy sulfosuccinate, etc. can be used in place of the Alipal and the Benax 2A1 (sodium dodecyl diphenyl ether disulfonate), the particular type of surfactant not being critical. The mixture of furfuryl and tetrahydrofurfuryl alcohols with or without humectant inherently catalyzes the cleaning action of the caustic without the surfactants but they are very helpful in increasing penetration into the grease. Also, the humectant inherently increases the cleaning effect of the hydroxide and reduces its irritating effect on the skin with or without surfactants. Anionic surfactants are preferred.

The amount of surfactant is not critical. In fact, as aforesaid, it can be eliminated entirely without affecting the action on the caustic of the catalyst and/ or the humectant. When it is used it may be present from 0.1% by weight to 4 or 5% or more limited only by the mutual compatibility thereof with the rest of the formula.

All or part of the sodium hydroxide can be replaced by other alkali metal hydroxides, e.g. potassium hydroxide.

One of the main advantages of the composition of the present invention is its reduced caustic content made possible by the catalyzing action of the furfuryl and tetrahydrofurfuryl alcohols and by the action of the humectant. This action occurs with any amount of caustic and with small amounts of catalyst. It has been found that 3% by weight of caustic gives excellent results. From a commercially practical standpoint a concentration of between 1 and 2% may be considered as a lower limit, although the cleaning action of even smaller amounts is increased by the presence of the furfuryl and tetrahydrofurfuryl alcohols and/ or the presence of the humectant so that the benefits of the invention are achieved to some extent. Although, as aforesaid, one of the chief advantages of the invention is to permit a reduction in caustic concentration for reasons given above (concentrations of 3% to 5 or 6% or 7% provide such reduction), the cleaning action of the caustic is increased and hence enhanced with a 10% caustic content, which is the maximum permitted by law without undesirable stringent labelling requirements, and even greater concentrations so that the benefits of this aspect of the invention are achieved with any caustic concentration.

It has been found that a mixture of furfuryl and tetrahydrofurfuryl alcohols in a ratio greater than 1 to 1 give the most marked results. Preferably, such ratio is at least 2. to 1. The results achieved with only one of them are not as marked but nevertheless noticeably improved results are achieved with the use of only one of them as compared to the use of caustic alone or caustic with humectant. The results achieved with equal amounts or a greater amount of tetrahydrofurfuryl alcohol are better than with just one but not as good as with an excess of furfuryl over the tetrahydrofurfuryl alcohol.

There is no upper or lower limit to the amount of furfuryl and tetrahydrofurfufyl alcohol which can be used except from a practical standpoint. Even trace amounts will provide some catalytic action. A preferred concentration range for the mixture of catalytic alcohols is between about 0.1% and 5% by weight of the compositions. Increases above five percent do not provide sufficient further advantages to warrant the increased cost at least with amounts of caustic less than 10%. The maximum amount except for expense is dictated by the mutual compatibility of the alcohols with the balance of the formula.

It is pointed out that the catalytic action of the furfuryl and tetrahydrofurfuryl alcohols is unique with them and has not been found to be a property of other alcohols.

The solids concentration of the composition is preferably not much more than 10 or 12% by weight of the composition and, more preferably, not much greater than 5%. In the above example, the sodium hydroxide is the only solid since the surfactants are liquids. However, solid surfactants may be used.

The carrier or solvent in the example is water. The water carrier makes up the balance of the composition.

The water carrier may range from about 95% to 50% (approximately one half) by weight but more preferably between 70 and Inherently, the water, by ionizing the hydroxide, permits the hydroxide to perform its optimum cleaning function, whereas the humectant, by inherently delaying evaporation of the water by contact with the hot oven surface, permits this action of the ionized hydroxide to continue for a suflicient length of time for optimum performance.

Although solutions are preferred, dispersions can also be used.

Preferably, the viscosity of the composition should be low enough to permit practical use of the composition 5 a spray and in aerosol spray cans.

The composition should be free from materials which may be harmful when applied hot or to hot surfaces and which will prevent the use of the composition as a spray or in aerosol containers. For example, it should be free from substantial amounts of nitrite and/or nitrate because they tend to blacken chrome, stainless steel, zinc, aluminum and other metals which are associated with ovens and from which grills may be made and because the heat is apt to decompose them into gases which have obnoxious odors and which may, under some circumstances, be poisonous. Also, nitrates and nitrites in combination with organic matter at elevated tempertures could result in explosive conditions. Of course, minute amounts of such compounds may be tolerated but not substantial amounts.

As aforesaid, the composition is applied to the oven and grill surfaces at an elevated temperature, i.e., to the hot oven. The particular elevated temperature is not critical. The maximum temperature is that at which the ingredients commence to decompose. As the temperature is decreased below 160 F. the results are not nearly so spectacular and at temperatures much below 140 F. the results are not much better than at room temperature. A temperature of roughly between about 180 F. and 2 or 210 F. is preferred and is recommended to the consumer, i.e., it is recommended to apply the composition to an oven set at 200 F. The only reason why a higher setting is not recommended is to avoid possible burning by touching the hot oven surfaces with the hands during application and removal of the composition. However, the setting could be the highest oven setting. The 200 F. setting is usually the lowest oven setting. However, if the oven has a setting of 180 F. or 160 F. or even lower, it could beset for that temperature during cleaning.

In the directions for use on the containers for the composition sold on the market it is recommended that the composition be wiped off 5 minutes after it is applied or minutes on heavily soiled areas. It is also stated that the composition can be normally used without rubber gloves, i.e., unless the user has abnormally sensitive skin. It is believed that the composition does not iritate or burn the skin because of the lower caustic concentration and the presence of the humectant. It is believed that the humectant ties up the caustic in some way at normal temperatures to thereby reduce its irritating effect but at the elevated temperature of the hot oven' surface, it is released for cleaning. However, this is merely a theoretical explanation.

Where the hydrofurfuryl alcohol and tetrahydrofurfuryl alcohol were omitted from the composition of the example, cleaning was not as good but it was still markedly better and faster, when applied as a foam or spray to the hot oven surfaces, than that of all oven cleaners known prior to the present invention. Accordingly, this composition and method are contemplated by the present invention.

Where the evaporation retardant or humectant was omitted, cleaning was not as good either because the water evaporates before optimum cleaning can be achieved but, when applied as a foam or spray to the hot oven surface, it was still markedly better and faster than that of all oven cleaners known prior to the present invention. Accordingly, this composition and method are contemplated by the present invention.

Where the hydrofurfuryl alcohols and the humectant were both omitted, cleaning was not nearly as good as when either of them are present but, when applied as a foam or spray to the hot oven surfaces, it was still better and faster than that of all oven cleaners known prior to the present invention. Accordingly, this composition and method are contemplated by the present invention.

The above examples and description are for purposes of illustration only and it is not intended that the invention be limited thereto, such invention being limited only to the compositions and methods claimed in the following claims and their equivalents.

I claim:

1. A method of cleaning ovens and grills comprising spraying on the oven or grill, while the oven or grill is at an elevated temperature, a liquid composition consisting essentially of water and an alkali metal hydroxide in which at least about one half of the composition by Weight is water and in which the amount of alkali metal hydroxide is between about 1% and 10% by weight, leaving said composition on the hot oven for an interval of time and removing said composition from said oven, said composition being sprayed from an aerosol container by a propellant contained in said container, said water and hydroxide concentrations being exclusive of propellant, the amount of said propellant being sufiicient to force said composition out of said container as a spray.

2. A method according to claim 1, said composition containing a compatible surfactant stable in said composition and being sprayed on said oven while said oven is at least about F., said surfactant being selected from the group consisting of anionic, cationic and nonanionic surfactants, said composition including a humectant selected from the group consisting of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

3. A- method according to claim 1, said composition including a polyhydric alcohol humectant.

4. A method according to claim 3, said humectant being selelcted from the group consisting of a glycol and a glycero 5. A method according to claim 3, said composition also containing a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group consisting of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

6. A method according to claim 5, said composition 1tg eing sprayed on said oven while said oven is at least 140 7. A method according to claim 3, said composition also containing a catalyst for said hydroxide selected from the group consisting of furfuryl alcohol, hydrofurfuryl alcohol and a mixture thereof.

8. A method according to claim 7, the amount of said catalyst not exceeding about 5% by weight of said composition exclusive of propellant.

9. A method according to claim 8, said catalyst consisiing of a mixture of furfuryl and hydrofurfuryl alcoho s.

10. A method according to claim 8, said humectant being selected from the group consisting of a glycol and and glycerol and said composition including a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group consisting of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

11. A method according to claim 1, said composition including a catalyst for said hydroxide selected from the group consisting of furfuryl alcohol, hydrofurfuryl alcohol and a mixture thereof.

12. A method according to claim 11, the amount of said catalyst not exceeding by weight of said composition exclusive of propellant.

13. A method according to claim 12, said catalyst consisting of a mixture of furfuryl and hydrofurfuryl alcohols.

14. A method according to claim 1, said composition being applied to said oven while said oven is at least 140 F., the concentration of said alkali metal hydroxide being between 1% and 7%.

15. A method according to claim 12, said composition containing a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group consisting of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

16. An oven and grill cleaner in liquid form for application to a hot oven or grill consisting essentially of water and alkali metal hydroxide packaged in an aerosol container also containing a propellant, the amount of alkali metal hydroxide being between about 1% and by weight of the composition exclusive of propellant, at least about one half of said composition by Weight, exclusive of propellant, being water, the amount of said propellant being suflicient to force said composition out of said container as a spray.

17. A cleaner according to claim 16, said cleaner also containing a polyhydric alcohol humectant.

18. A cleaner according to claim 17, said humectant being selected from the group consisting of a glycol and a glycerol.

19. A cleaner according to claim 17, said cleaner containing a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group cosistig of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by Weight exclusive of propellant.

20. A cleaner according to claim 17, said composition containing a catalyst selected from the group consisting of furfuryl alcohol, hydrofurfuryl alcohol and a mixture thereof.

21. A cleaner according to claim 20, the amount of catalyst not exceeding about 5% by weight of said composition exclusive of propellant.

22. A cleaner according to claim 20, said catalyst consisting of a mixture of furfuryl alcohol and tetrahydrofurfuryl alcohols.

23. A cleaner according to claim 20, said composition also including a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group consisting of glycol and a glycerol, the alkali metal 8 hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

24. A cleaner according to claim 16, said composition including a catalyst of the group consisting of furfuryl alcohol, hydrofurfuryl alcohol and a mixture thereof.

25. A cleaner according to claim 24, the amount of catalyst not exceeding 5% by weight of said composition, exclusive of propellant.

26. A cleaner according to claim 16, the amount of said alkali metal hydroxide being between 1% and 7% by weight of the composition exclusive of propellant.

27. A cleaner according to claim 25, said composition including a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group consisting of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

28. A cleaner according to claim 16, said composition containing a compatible surfactant stable in said composition, said surfactant being selected from the group consisting of anionic, cationic and nonionic surfactants, said composition including a humectant selected from the group consisting of a glycol and a glycerol, the alkali metal hydroxide being sodium hydroxide present in an amount of 3% by weight exclusive of propellant.

29. A method according to claim 1 wherein the alkali metal hydroxide is present in an amount of from 1% to 3% and where the alkali metal hydroxide is sodium hydroxide.

30. A cleaner according to claim 17 wherein the alkali metal hydroxide is present in an amount of from 1% to 3% by weight exclusive of propellant and the alkali metal hydroxide is sodium hydroxide.

31. A method according to claim 5 wherein the humectant is propylene glycol.

32. A cleaner according to claim 19 wherein the humectant is propylene glycol.

References Cited UNITED STATES PATENTS 2,662,837 12/1953 Duncan 252-158 X 2,892,795 6/1959 Dalton 252138 2,992,995 7/1961 Arden 252156 X 3,031,408 4/1962 Perlman et al. 252l58 X 3,031,409 4/1962 Perlman et al. 252l58 3,145,178 8/1964 Dupre et a1. 252156 FOREIGN PATENTS 825,960 12/1959 Great Britain.

LEON D. ROSDOL, Primary Examiner.

JULIUS GREENWALD, Examiner.

I. T. FEDIGAN, Assistant Examiner. 

1. A METHOD OF CLEANING OVENS AND GRILLS COMPRISING SPRAYING ON THE OVEN OR GRILL, WHILE THE OVEN OR GRILL IS AT AN ELEVATED TEMPERATURE, A LIQUID COMPOSITION CONSISTING ESSENTIALLY OF WATER AND AN ALKALI METAL HYDROXIDE IN WHICH AT LEAST ABOUT ONE HALF OF THE COMPOSITION BY WEIGHT IS WATER AND IN WHICH THE AMOUNT OF ALKALI METAL HYDROXIDE IS BETWEEN ABOUT 1% AND 10% BY WEIGHT, LEAVING SAID COMPOSITION ON THE HOT OVEN FOR AN INTERVAL OF TIME AND REMOVING SAID COMPOSITION FROM SAID OVEN, SAID COMPOSITION BEING SPRAYED FROM AN AEROSOL CONTAINER BY A PROPELLANT CONTAINED IN SAID CONTAINER, SAID WATER AND HYDROXIDE CONCENTRATIONS BEING EXCLUSIVE OF PROPELLANT, THE AMOUNT OF SAID PROPELLANT BEING SUFFICIENT TO FORCE SAID COMPOSITION OUT OF SAID CONTAINER AS A SPRAY.
 3. A METHOD ACCORDING TO CLAIM
 1. SAID COMPOSITION INCLUDING A POLYHYDRIC ALOCHOL HUMECTANT. 